Systems for receiving digital television signals are well known. In one common end-user configuration, such as may be seen in FIG. 1, a home video server 100 employs a tuner 102 to receive a digital television broadcast signal via a satellite receiver 104. The signal data, such as a scrambled MPEG-2 packet stream, may be stored on a storage medium 110, descrambled and decoded by an MPEG decoder 106 for viewing on a television 108, and transmitted in scrambled form via a transmitter 112 to a client 114. Client 114 may similarly descramble and decode the scrambled packet stream at an MPEG decoder 116 for viewing on a television 118.
When transmitting to client 114, it is advantageous to transmit the MPEG-2 packet stream in scrambled form in support of anti-piracy measures. However, current solutions for providing trick mode support to clients, such as fast-forward viewing, require a) changing the transmission rate, or b) descrambling the packet stream at the video server, modifying the video content to support the trick mode, and either b1) transmitting the descrambled and modified video to the client, or b2) rescrambling and transmitting the modified video to the client. Unfortunately, the existing bandwidth between the server and the client is often insufficient to support an accelerated transmission rate, transmitting descrambled video to the client defeats anti-piracy measures, and existing home video servers are generally incapable of scrambling, and the cost and complexity of adding scrambling functionality to existing hardware, or replacing existing hardware with hardware having scrambling capability, may be prohibitive.
Trick mode support for scrambled packet streams that takes advantage of existing bandwidth, that provides for transmission of scrambled packet streams to clients, and that does not require rescrambling at the end-user video server would therefore be advantageous.